Currently
https://github.com/ros-planning/navigation2/blob/master/nav2_amcl/package.xml#L21
says only LGPL, while:
https://github.com/ros-planning/navigation2/blob/master/nav2_amcl/src/main.cpp#L3
https://github.com/ros-planning/navigation2/blob/master/nav2_amcl/test/unit/test_localization_amcl.cpp#L3
says Apache-2
https://github.com/ros-planning/navigation2/blob/master/nav2_amcl/src/amcl_node.cpp#L5
https://github.com/ros-planning/navigation2/blob/master/nav2_amcl/include/nav2_amcl/amcl_node.hpp#L5
says LGPL-2.1+

superflore maps this to LGPL-2 in:
https://github.com/ros-infrastructure/superflore/blob/master/superflore/utils.py#L179
and LGPL-2 isn't valid SPDX Identifier in:
https://spdx.org/licenses/
so it would be better to declare the license correctly at the source - in package.xml.

I've already reported this in:
ros2-gbp/navigation2-release#1
but was redirected to here.